Authors:Congbing Fang, Xiaochun Wan, Changjun Jiang, Huarong Tan, Yinghui Hu, and Haiqun Cao
To evaluate the reliability and applicability of chromatographic methods for fingerprinting, and for obtaining comprehensive information from the fingerprint, several chromatographic techniques including high-performance thin-layer chromatography (HPTLC), high-performance liquid chromatography (HPLC), and high-performance capillary electrophoresis (HPCE) have been used to obtain fingerprints of
for the first time. The results showed that the relative standard deviation (
values, retention times, and peak-area percentages for samples of
from different sources all perfectly satisfied the demands of the national standard, and HPTLC, HPLC, and HPCE have been successfully used for development of fingerprints of
. When the chromatographic fingerprints established in this work were used to distinguish between authentic and fake
by evaluation of similarity, different samples obtained from
were distinguished effectively. Although the three methods used for fingerprinting of
were highly selective and reproducible, there were still significant reliability and applicability differences among the results obtained by use of these approaches, as is illustrated in this paper.
Authors:G. Klunder, J. Andrews, M. Church, J. Spear, R. Russo, P. Grant, and B. Andresen
Capillary electrophoresis has been used to separate metal ions characteristically associated with nuclear fission. Electrokinetic
injections and transient isotachophoretic techniques were employed to increase sample loading and provide on-column concentration
of the analyte. On-line concentration factors of approximately 700-fold have been achieved. Indirect-UV absorbance, on-line
radioactivity, and indirect laser-induced fluorescence detection were used to monitor analytes of interest. The radioactivity
detector consists of a plastic scintillator and photomultiplier tube with a 4π detection geometry. The efficiency was determined
to be approximately 80%, enabling samples resident in the detector window for 0.1 minutes to be reliably assayed. Detection
of152Eu and137Cs was achieved at the low nCi level. Indirect fluorescence was performed with quinine sulfate as the background fluorophor
with α-hydroxysobutyric acid added as a complexing agent. An argon ion laser was used as the excitation source with a diode
array detector. Limits of detection for La3+, Ce3+, Pr3+, Nd3+, Sm3+, and Eu3+ were determined to be in the sub — 10 ppb range (6–11 nM) with indirect laser-induced fluorescence detection.
Authors:E. Dadáková, N. Vrchotová, Š. Chmelová, and B. Šerá
Black elder inflorescence has been traditionally used in Central Europe both in folk and official medicine. This plant material is a rich source of two biologically active components, rutin and chlorogenic acid. Nevertheless, there is a lack of data on the changes of their content during processing.The stability of rutin and chlorogenic acid during drying and the long-term storage of black elder inflorescence were analysed in this study. The rutin content was determined by capillary electrophoresis using solid-phase extraction. HPLC was used for the determination of chlorogenic acid. The dependence of rutin and chlorogenic acid content on the temperature of drying and storage duration were monitored and statistically evaluated by a two-way ANOVA test. The contents of rutin and chlorogenic acid revealed no statistically significant changes when dried at temperatures of 22 °C and 30 °C. The significant decrease in contents of both studied compounds was found at a drying temperature of 50 °C. The decrease in content of rutin was about 20%, in chlorogenic acid about 12%.The content of both studied compounds also decreased after long-term storage (at a temperature of 22 °C for one year). The decrease in content of rutin was greater than that of chlorogenic acid.
Authors:Gergely Zachar, Tamás Jakó, István Vincze, Zsolt Wagner, Tamás Tábi, Eszter Bálint, Szilvia Mezey, Éva Szökő, and András Csillag
D-aspartate (D-Asp) modulates adult neural plasticity and embryonic brain development by promoting cell proliferation, survival and differentiation. Here, developmental changes of the excitatory amino acids (EAAs) L-Glu, L-Asp and D-Asp were determined during the first postembryonic days, a time window for early learning, in selected brain regions of domestic chickens after chiral separation and capillary electrophoresis. Extracellular concentration (ECC) of EAAs was measured in microdialysis samples from freely moving chicks. ECC of D-Asp (but not L-EAAs) decreased during the first week of age, with no considerable regional or learning-related variation. ECC of L-Asp and L-Glu (but not of D-Asp) were elevated in the mSt/Ac in response to a rewarding stimulus, suggesting importance of Asp-Glu co-release in synaptic plasticity of basal ganglia. Potassium-evoked release of D-Asp, with a protracted transient, was also demonstrated. D-Asp constitutes greater percentage of total aspartate in the extracellular space than in whole tissue extracts, thus the bulk of D-Asp detected in tissue appears in the extracellular space. Conversely, only a fraction of tissue L-EAAs can be detected in extracellular space. The lack of changes in tissue D-Asp following avoidance learning indicates a tonic, rather than phasic, mechanism in the neuromodulatory action of this amino acid.
Authors:L. Simon-Sarkadi, É. Gelencsér, and A. Vida
Kovács, Á., Simon-Sarkadi, L. & Ganzler, K. (1999): Determination of biogenic amines by capillaryelectrophoresis. J. Chrom. A , 836 , 305-313.
Determination of biogenic amines by capillaryelectrophoresis
Mierzejewska, D., Panasiuk, R. & Jéddrychowski, L. (2002): Capillaryelectrophoresis determination of denaturation degree of cow milk α-lactalbumin during heat treatment of whey. Milchwissenschaft , 57 , 9-13.
Enantiomer separations have been one of the most important and, simultaneously, one of the most difficult to accomplish analytical (and technological) tasks, present at the top of separation scientists' agenda since the early sixties of the last century. Awareness of their importance has been awakened by an infamous case of the racemic drug thalidomide, a widely advertised sedative drug which had unexpected teratogenic activity in pregnant women that resulted in thousands of ‘flipper babies’ born in the late fifties and the early sixties in many countries around the world. Since that time, separation scientists have developed numerous methods for enantiomer separation, basically by use of gas chromatography (GC), high-performance liquid chromatography (HPLC), and capillary electrophoresis (CE). In this respect, planar chromatography has remained to a large extent an undervalued enantiomer separation technique, despite separation performance sufficient to separate a pair of enantiomers. The large number of GC, HPLC, and CE enantiomer separation strategies and methods developed are evidence that — once confronted with this particular and no doubt very important challenge — instrumental chromatographic techniques have lost if not face, then, to a large extent, their reputation as robust, universal, and efficient separation tools. In these circumstances, planar chromatography on silica gel seems a very promising and tempting alternative, basically because of the advantageous properties of microcrystalline silica gel and the 2D effective diffusion available only in planar chromatographic mode. Enhancement of the enantiomer separating power of the silica gel by simple mechanical impregnation with a properly chosen chiral selector, and additional coupling of this with efficient instrumental detection (e.g. densitometric, DAD, or mass spectrometric) can yield in a simple, robust, and universal tool for separation of enantiomers comparable with the long-established chromatographic enantiomer-separation techniques. In this mini review, favourable preconditions for silica-gel-based planar chromatographic separation of enantiomers which can elevate planar chromatography to the status of leading tool for separation of enantiomers are discussed. Further improvements which can enhance the enantiomer separation performance of chiral planar chromatography are also indicated.